1. Field of the Invention
This invention relates to pattern identification systems and particularly to a minutiae pattern identification system which in one embodiment automatically determines whether the minutiae pattern of an unidentified fingerprint matches that of any one of a plurality of known reference fingerprints.
2. Description of the Prior Art
The necessity for accurate and automatic fingerprint identification or verification in the fields of law enforcement, security, credit transactions, etc., has increased with time. Many different types of automatic systems have been proposed for identifying fingerprints or other patterns in these fields.
A first type of automatic fingerprint identification system is based primarily upon the global or general form of fingerprint patterns in order to determine the degree of match between those fingerprint patterns. Most systems based upon optical or holographic pattern matching are included in this first type. Examples of this first type of system are described in U.S. Pat. Nos.: 3,200,701; 3,292,149; 3,511,571; 3,532,426; 3,614,737; 3,619,060; 3,622,989; 3,704,949; 3,743,421; and 3,781,113.
A second type of automatic fingerprint identification system is based primarily upon local characteristics or details of the fingerprint patterns, e.g. the encoding of certain nuances in the vicinity of a fingerprint core. Examples of this second type of system are described in U.S. Pat. Nos. 3,584,958 and 3,694,240. In each of these two patents a mask is provided with a reference opening of predetermined contour for forming a reference line of corresponding contour across the fingerprint of an individual. This reference line will intersect the lines making up the fingerprint at some definite number of locations to define areas of intersection. These areas of intersection form the basis for parallel code lines of different widths for an identification card for the individual. A subsequent identification of the individual will be made by comparing the code lines of the identification card with the individual's fingerprint as taken at the time the card is used.
A third type of automatic fingerprint identification system is based upon a combination of the global form of the fingerprint patterns and local fingerprint characeristics which do not utilize minutiae. The minutiae of a fingerprint comprise the finest details that can be extracted from the fingerprint. Examples of this third type are found in U.S. Pat. Nos. 2,952,181; 3,566,354; 3,771,124 and 3,882,462. Each of these patents uses concatenated local information consisting of ridge and frequency measurements as the characterizing information. This breaking up of the ridge flow into local regions, is superior to a purely global approach,. In another example, U.S. Pat. No. 3,716,301 is concerned with a global correlation technique with a quasi-local embellishment consisting of one or more information bands around a central region.
A fourth type of automatic fingerprint identification system is based upon a combination of the global form of the fingerprint patterns and utilizes minutiae is the local fingerprint characteristics.
One example of this fourth type is found in U.S. Pat. No. 3,582,889. The fifth circuit of this patent utilizes a group of minutiae (termed "characteristic points") to form a "closed figure with straight sides joining the points in a predetermined order". The sixth circuit of this patent indicates coincidence of an unknown pattern with a known pattern when a preselected number of such closed figures are common to the two patterns.
Another example of this fourth type is described in "Automated Fingerprint Identification", by J. H. Wegstein, NBS (National Bureau of Standards) Technical Note 538, SD Catalog No. C13.46.538, U.S. Government Printing Office, Washington, D.C., August 1970. In this publication an NBS system is described which uses minutiae data for the entire fingerprint without doing a specific local region.
Many of the above-described systems require a relatively close orientation of the finger to be identified with the apparatus which is to perform the fingerprint identification.
None of the systems discussed above performs a relative information vector (RIV) encoding and analysis of minutiae neighborhoods of the fingerprints being compared to determine how each and every little minutiae neighborhood, or RIV, or one fingerprint matches with each and every little region of the other fingerprint. None of the above-described systems puts all these interim RIV comparison results together in three dimensional space to obtain the global picture.